NAME
ntpq - standard Network Time Protocol query program
SYNOPSIS
ntpq [ -inp ] [ -c command ] [ host ] [ ... ]
DESCRIPTION
Ntpq is used to query NTP servers which implement the
recommended NTP mode 6 control message format about current
state and to request changes in that state. The program may
be run either in interactive mode or controlled using
command line arguments. Requests to read and write arbitrary
variables can be assembled, with raw and pretty-printed
output options being available. Ntpq can also obtain and
print a list of peers in a common format by sending multiple
queries to the server.
If one or more request options is included on the command
line when ntpq is executed, each of the requests will be
sent to the NTP servers running on each of the hosts given
as command line arguments, or on localhost by default. If no
request options are given, ntpq will attempt to read
commands from the standard input and execute these on the
NTP server running on the first host given on the command
line, again defaulting to localhost when no other host is
specified. Ntpq will prompt for commands if the standard
input is a terminal device.
Ntpq uses NTP mode 6 packets to communicate with the NTP
server, and hence can be used to query any compatable server
on the network which permits it. Note that since NTP is a
UDP protocol this communication will be somewhat unreliable,
especially over large distances in terms of network
topology. Ntpq makes one attempt to retransmit requests,
and will time requests out if the remote host is not heard
from within a suitable time out time.
Command line options are described following. Specifying a
command line option other than -i or -n will cause the
specified query (queries) to be sent to the indicated
host(s) immediately. Otherwise, ntpq will attempt to read
interactive format commands from the standard input.
-c The following argument is interpreted as an
interactive format command and is added to the list
of commands to be executed on the specified host(s).
Multiple -c options may be given.
-i Force ntpq to operate in interactive mode. Prompts
will be written to the standard output and commands
read from the standard input.
-n Output all host addresses in dotted-quad numeric
format rather than converting to the canonical host
names.
-p Print a list of the peers known to the server as
well as a summary of their state. This is equivalent
to the "peers" interactive command.
INTERNAL COMMANDS
Interactive format commands consist of a keyword followed by
zero to four arguments. Only enough characters of the full
keyword to uniquely identify the command need be typed. The
output of a command is normally sent to the standard output,
but optionally the output of individual commands may be sent
to a file by appending a ">", followed by a file name, to
the command line.
A number of interactive format commands are executed
entirely within the ntpq program itself and do not result in
NTP mode 6 requests being sent to a server. These are
described following.
? [ command_keyword }
A "?" by itself will print a list of all the command
keywords known to this incarnation of ntpq. A "?" followed
by a command keyword will print funcation and usage
information about the command. This command is probably a
better source of information about ntpq than this manual
page.
timeout millseconds
Specify a time out period for responses to server queries.
The default is about 5000 milliseconds. Note that since ntpq
retries each query once after a time out the total waiting
time for a time out will be twice the time out value set.
delay milliseconds
Specify a time interval to be added to timestamps included
in requests which require authentication. This is used to
enable (unreliable) server reconfiguration over long delay
network paths or between machines whose clocks are
unsynchronized. Actually the server does not now require
time stamps in authenticated requests, so this command may
be obsolete.
host hostname
Set the host to which future queries will be sent. Hostname
may be either a host name or a numeric address.
poll [ # ] [ verbose ]
Poll the current server in client mode. The first argument
is the number of times to poll (default is 1) while the
second argument may be given to obtain a more detailed
output of the results. This command is currently just
wishful thinking.
keyid #
This command allows the specification of a key number to be
used to authenticate configuration requests. This must
correspond to a key number the server has been configured to
use for this purpose.
passwd
This command prompts you to type in a password (which will
not be echoed) which will be used to authenticate
configuration requests. The password must correspond to the
key configured for use by the NTP server for this purpose if
such requests are to be successful.
hostnames yes|no
If "yes" is specified, host names are printed in information
displays. If "no" is given, numeric addresses are printed
instead. The default is "yes" unless modified using the
command line -n switch.
raw
Causes all output from query commands is printed as received
from the remote server. The only formating/intepretation
done on the data is to transform nonascii data into a
printable (but barely understandable) form.
cooked
Causes output from query commands to be "cooked". Variables
which are recognized by the server will have their values
reformatted for human consumption. Variables which ntpq
thinks should have a decodeable value but didn't are marked
with a trailing "?".
ntpversion 1|2|3
Sets the NTP version number which ntpq claims in packets.
Defaults to 3, Note that mode 6 control messages (and modes,
for that matter) didn't exist in NTP version 1. There appear
to be no servers left which demand version 1.
authenticate yes|no
Normally ntpq does not authenticate requests unless they are
write requests. The command authenticate yes causes ntpq to
send authentication with all requests it makes.
Authenticated requests causes some servers to handle
requests slightly differently, and can occasionally melt the
CPU in fuzzballs if you turn authentication on before doing
a peer display.
addvars <variable_name>[=<value>][,...] rmvars
<variable_name>[,...] clearvars
The data carried by NTP mode 6 messages consists of a list
of items of the form
<variable_name>=<value>
where the "=<value>" is ignored, and can be omitted, in
requests to the server to read variables. Ntpq maintains an
internal list in which data to be included in control
messages can be assembled, and sent using the readlist and
writelist commands described below. The addvars command
allows variables and their optional values to be added to
the list. If more than one variable is to be added, the list
should be comma-separated and not contain white space. The
rmvars command can be used to remove individual variables
from the list, while the clearlist command removes all
variables from the list.
debug more|less|off
Turns internal query program debugging on and off.
quit
Exit ntpq.
CONTROL MESSAGE COMMANDS
Each peer known to an NTP server has a 16 bit integer
association identifier assigned to it. NTP control messages
which carry peer variables must identify the peer the values
correspond to by including its association ID. An
association ID of 0 is special, and indicates the variables
are system variables, whose names are drawn from a separate
name space.
Control message commands result in one or more NTP mode 6
messages being sent to the server, and cause the data
returned to be printed in some format. Most commands
currently implemented send a single message and expect a
single response. The current exceptions are the peers
command, which will send a preprogrammed series of messages
to obtain the data it needs, and the mreadlist and mreadvar
commands, which will iterate over a range of associations.
associations
Obtains and prints a list of association identifiers and
peer statuses for in-spec peers of the server being queried.
The list is printed in columns. The first of these is an
index numbering the associations from 1 for internal use,
the second the actual association identifier returned by the
server and the third the status word for the peer. This is
followed by a number of columns containing data decoded from
the status word. Note that the data returned by the
"associations" command is cached internally in ntpq. The
index is then of use when dealing with stupid servers which
use association identifiers which are hard for humans to
type, in that for any subsequent commands which require an
association identifier as an argument, the form &index may
be used as an alternative.
lassocations
Obtains and prints a list of association identifiers and
peer statuses for all associations for which the server is
maintaining state. This command differs from the
"associations" command only for servers which retain state
for out-of-spec client associations (i.e. fuzzballs). Such
associations are normally omitted from the display when the
"associations" command is used, but are included in the
output of "lassociations".
passociations
Prints association data concerning in-spec peers from the
internally cached list of associations. This command
performs identically to the "associations" except that it
displays the internally stored data rather than making a new
query.
lpassociations
Print data for all associations, including out-of-spec
client associations, from the internally cached list of
associations. This command differs from "passociations" only
when dealing with fuzzballs.
pstatus assocID
Sends a read status request to the server for the given
association. The names and values of the peer variables
returned will be printed. Note that the status word from the
header is displayed preceding the variables, both in
hexidecimal and in pidgeon English.
readvar [ assocID ] [ <variable_name>[=<value>][,...] ]
Requests that the values of the specified variables be
returned by the server by sending a read variables request.
If the association ID is omitted or is given as zero the
variables are system variables, otherwise they are peer
variables and the values returned will be those of the
corresponding peer. Omitting the variable list will send a
request with no data which should induce the server to
return a default display.
rv [ assocID ] [ <variable_name>[=<value>][,...] ]
An easy-to-type short form for the readvar command.
writevar assocID <variable_name>=<value>[,...]
Like the readvar request, except the specified variables are
written instead of read.
readlist [ assocID ]
Requests that the values of the variables in the internal
variable list be returned by the server. If the association
ID is omitted or is 0 the variables are assumed to be system
variables. Otherwise they are treated as peer variables. If
the internal variable list is empty a request is sent
without data, which should induce the remote server to
return a default display.
rl [ assocID ]
An easy-to-type short form of the readlist command.
writelist [ assocID ]
Like the readlist request, except the internal list
variables are written instead of read.
mreadvar assocID assocID [ <variable_name>[=<value>][,...]
]
Like the readvar command except the query is done for each
of a range of (nonzero) association IDs. This range is
determined from the association list cached by the most
recent associations command.
mrv assocID assocID [ <variable_name>[=<value>][,...] ]
An easy-to-type short form of the mreadvar command.
mreadlist assocID assocID
Like the readlist command except the query is done for each
of a range of (nonzero) association IDs. This range is
determined from the association list cached by the most
recent associations command.
mrl assocID assocID
An easy-to-type short form of the mreadlist command.
clockvar [ assocID ] [ <variable_name>[=<value>][,...] ]
Requests that a list of the server's clock variables be
sent. Servers which have a radio clock or other external
synchronization will respond positively to this. If the
association identifier is omitted or zero the request is for
the variables of the "system clock" and will generally get a
positive response from all servers with a clock. If the
server treats clocks as pseudo-peers, and hence can possibly
have more than one clock connected at once, referencing the
appropriate peer association ID will show the variables of a
particular clock. Omitting the variable list will cause the
server to return a default variable display.
cv [ assocID ] [ <variable_name>[=<value>][,...] ]
An easy-to-type short form of the clockvar command.
peers
Obtains a list of in-spec peers of the server, along with a
summary of each peer's state. Summary information includes
the address of the remote peer, the reference ID (0.0.0.0 if
the refID is unknown), the stratum of the remote peer, the
type of the peer (local, unicast, multicast or broadcast),
when the last packet was received, the polling interval, in
seconds, the reachability register, in octal, and the
current estimated delay, offset and dispersion of the peer,
all in seconds.
The character in the left margin indicates the fate of this
peer in the clock selection process. The codes mean: <sp>
discarded due to high stratum and/or failed sanity checks;
"x" designated falsticker by the intersection algorithm; "."
culled from the end of the candidate list; "-" discarded by
the clustering algorithmi; "+" included in the final
selection set; "#" selected for synchronizatio;n but
distance exceeds maximum; "*" selected for synchronization;
and "o" selected for synchronization, pps signal in use.
Note that since the peers command depends on the ability to
parse the values in the responses it gets it may fail to
work from time to time with servers which poorly control the
data formats.
The contents of the host field may be one of four forms. It
may be a host name, an IP address, a reference clock
implementation name with its parameter or
"REFCLK(<implementation number>, <parameter>)". On
"hostnames no" only IP-addresses will be displayed.
lpeers
Like peers, except a summary of all associations for which
the server is maintaining state is printed. This can produce
a much longer list of peers from fuzzball servers.
opeers
An old form of the "peers" command with the reference ID
replaced by the local interface address.
HISTORY
Written by Dennis Ferguson at the University of Toronto.
BUGS
The peers command is non-atomic and may occasionally result
in spurious error messages about invalid associations
occurring and terminating the command.
The timeout time is a fixed constant, which means you wait a
long time for time outs since it assumes sort of a worst
case. The program should improve the time out estimate as it
sends queries to a particular host, but doesn't.